fix: let "Cover fees" checkbox work with any payment method

[dkoo]

All Submissions:

• [x] Have you followed the Newspack Contributing guideline?
• [x] Does your code follow the WordPress' coding standards and VIP Go coding standards?
• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Adds a custom payment fields checkout template for Woo. The only change in this template is to add a new action hook after the payment fields for each payment method. Supports changes in https://github.com/Automattic/newspack-plugin/pull/3491.

How to test the changes in this Pull Request:

See testing instructions in https://github.com/Automattic/newspack-plugin/pull/3491

Other information:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [ ] Have you written new tests for your changes, as applicable?
• [x] Have you successfully ran tests with your changes locally?

[matticbot]

:tada: This PR is included in version 4.2.4 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: